WHITE HOUSE U.S. President Donald Trump and South Korean leader Moon Jae-in are set to meet at the White House Tuesday amid increasing skepticism of the chances for a successful U.S.-North Korea summit and doubts the meeting will take place as planned.

During Tuesday's scheduled two hours of talks, Moon is expected to try to reassure Trump that next month's encounter with North Korean leader Kim Jong Un can lead to a historic breakthrough.

"I suspect President Trump has some tough questions for President Moon that he'd prefer to ask privately, given the lack of clarity on what the North Koreans will agree to � and the latest chess move by the North Koreans to threaten to cancel the June 12 summit," said Jean Lee, the Korea Center program director at the Wilson Center.

Trump, according to officials in the U.S. and abroad, has been questioning his aides and foreign leaders about whether he should proceed with going to Singapore to meet Kim.

Some officials in Washington, speaking on condition of not being named, also blame South Korean officials for initially overselling to Trump the willingness of the North Korean leader to denuclearize.

It is a view shared by some outsiders, as well.

"Moon likely exaggerated this to tie Trump to a diplomatic track to prevent him from backsliding into last year's war threats, which scared the daylights out of South Koreans," said Robert Kelly, a political science professor at Pusan National University.

Lee, a former Pyongyang bureau chief for the Associated Press, sees Moon as desiring to "jump in again to play the role of mediator, and to show that Seoul and Washington are in close coordination at the highest level, at least outwardly. But it will be a difficult conversation, I suspect."

Eager for U.S. involvement

In the view of some analysts, such as Institute for Corean-American Studies Fellow Tara O, Moon appears anxious to persuade Trump to go ahead with the Kim summit and to get the U.S. president to grant sanctions relief so planned joint South-North projects would be able to proceed.

As a result of last month's Panmunjom meeting between Moon and Kim, the two Koreas "provided a deadline for the signing of the peace treaty by this year, so Moon would also discuss that with Trump," O, the author of a book "The Collapse of North Korea: Challenges, Planning, and Geopolitics of Unification," tells VOA.

In her view, however, some in Washington may take a dim view of that, seeing the requests as premature "rewards for North Korea, which has not done anything to reduce the threat on the Korean Peninsula."

Lee, of the Wilson Center, contends "the North Koreans have skillfully played the situation by manufacturing an awkward moment between Moon and Trump just before their May 22 meeting. It's all part of the classic North Korean strategy of divide and conquer."

U.S. Vice President Mike Pence told Fox News that Trump could still walk away from the North Korea talks, and that their administration will not be fooled like those that came before them.

"We offered concessions to the North Korean regime in exchange for promises to end their nuclear weapons program, only to see them break promises and abandon them," Pence said. "It would be a great mistake for Kim Jong Un to think he could play Donald Trump."

Another key geopolitical player is China, whom Trump recently surmised influenced the statements coming out of Pyongyang casting doubt on the Singapore summit.

The president, on Twitter on Monday morning, called on China to keep its border tight with North Korea amid sanctions until he is able to reach an agreement with Kim.

The North Koreans have threatened to pull out of the talks with Trump, blaming what they term are demands by the United States for "unilateral nuclear abandonment."

Since that threat, Trump and others in the White House have denied they are demanding a so-called "Libya model" for disarmament, while still insisting North Korea must give up its nuclear weapons for which it would be richly rewarded.